Clinical Data

With median follow up of 3.2+ months, there was one partial response (PR, RECIST); this patient had a prostate-specific antigen (PSA) level drop from 98 to less than 1. Ten additional patients had tumor regression not meeting the criteria for PR. Seven patients have confirmed stable disease exceeding 6 months; one of these patients remains on therapy. Five patients have unconfirmed stable disease and continue on therapy. A total of 9 patients continue on therapy.

Gene expression profiling of tumor biopsies demonstrate a significant correlation of tumor CD73 expression with the adenosine signature (p=0.02). This correlation supports the relevance of adenosine in prostate cancer, its production by CD73 and the expression of adenosine induced immunosuppressive genes. Prior work in renal cell cancer, recently published in Cancer Discovery in January 2020, showed that the adenosine signature is associated with resistance to anti-PD(L)1 therapy, and predicted response to ciforadenant.

Treatment was well tolerated with 1 Grade 3 adverse event of fatigue in monotherapy and 1 Grade 3 adverse event of anemia in the combination arm.